The present invention relates to a cutting method of cutting or processing a predetermined portion of a device or the like uniformly in a direction of depth thereof by means of a focused charged particle beam such as a focused ion beam, and further relates to a secondary ion spectroscopic analysis method of analyzing secondary ions successively generated from the cut portion by use of the cutting method. More particularly, the present invention concerns the improvement in precision of cutting of a predetermined portion of a specimen or substrate in a direction of depth thereof.
The processing of a device by a focused charged particle beam such as a focused ion beam, for example, in order to cut off a wiring exposed on a device substrate or in order to expose a specified portion of a wiring buried in a device substrate to apply another wiring in a form extending or drawn out from the exposed portion is discussed by J. Vac. Sci. Technol. B4 (1986), pp. 176-180. In this prior art method, Ga is used as an ion species.
In the above-mentioned prior art method, no consideration is paid to the prevention of the aggregation or segregation of an irradiation ion species itself on a processed surface of a specimen or substrate or the prevention of the aggregation or segregation of an alloy, compound or the like resulting from the chemical coupling of an ion species and a device material, and hence it is difficult to maintain the precision of uniformity of the depth of a cut surface, as is shown in FIG. 1. Therefore, it is difficult to cut off a specified portion of a desired metal wiring provided in a device with a high precision or to expose only a specified portion of a desired metal wiring with a high precision. Further, also in a secondary ion spectroscopic analysis method of ion analyzing secondary charged ions generated from a specimen or substrate during the cutting of an object (specimen or substrate) by a focused charged particle beam such as a focused ion beam, no accurate uniformity of the object portion in a direction cf depth is obtainable and hence data acquired by that analysis method has a poor reliability in the direction of depth.